Analysis of the Oxidation Reduction Pote

The analysis of the variables, bacterial population, and oxidation-reduction potential (ORP) during the bioleaching of sulfide ores by a bacterial strain of Acidithiobacillus ferrooxidans, isolated from acid mine effluent, aims at the solubilization of copper and the liberation of the gold present in an ore containing more than 80% sulfides. It was studied at different pulp densities (1, 2, and 6% - W/V) and with a 9 k medium at different ferrous sulfate concentrations (0, 3, 6, 9, 12, and 15 g/L), keeping temperature and pH constant. The tests were carried out in three consecutive stages, starting with inoculum, whose cell content was 7.05x10⁷ Cell/mL, then the strain with the highest population obtained in the previous stage was used, observing the variation in the periods of adaptation and growth. During the bioleaching of sulfide ores, in the first stage, the maximum bacterial population achieved was 4.75x10⁷ Cell/mL in 24 days with 6 g/L ferrous sulfate, in the second stage, the maximum population was 6.30x10⁷ Cell/mL without the addition of ferrous sulfate, and in the third stage, the bacterial population became 4.51x10⁷ Cell/mL. The exponential characteristic growth of the population started at approximately 13, 8, and 3 days, respectively in each stage.